OBJECTIVES: Male teenagers used to smoke more than females, but this male:female ratio has reversed in several European countries over recent decades. The aim of this study was to assess whether a similar shift in gender differences in smoking and other health-related behaviours has occurred in Slovak adolescents over the last decade.STUDY DESIGN: Cross-sectional study.METHODS: Data were collected in 1998 (n=2616, 52.4% male, mean age 14.9±0.6 years, response rate 96.3%) and 2006 (n=1081, 47.0% male, mean age 14.3±0.6 years, response rate 93.0%). Changes in gender-specific prevalence rates for smoking, alcohol consumption and lack of physical activity were assessed for both cohorts overall and by socio-economic group using the highest educational level of the parents.RESULTS: Statistically significant changes occurred in the male:female ratios for smoking and lack of physical activity but not for alcohol consumption. The prevalence of smoking in males dropped below that in females, and the physical activity of females increased substantially. However, changes in gender ratios varied strongly by socio-economic group. The greatest shift in the gender ratio for smoking occurred in the middle socio-economic group, showing an increase in the entire sample. Changes in gender ratios over time among adolescents from the highest socio-economic group were much smaller.CONCLUSIONS: The behaviour of Slovak female adolescents has become similar to that of their male peers in terms of smoking and physical activity. This shift in the gender ratio in Slovakia over the last decade mimics the shift in Western Europe from approximately two decades ago.